The purpose of the proposed study is to examine the role of social stimuli in coordinating reproductive functions in rodents. This goal is approached by examining the role of social stimuli on the development of sexual maturity in females. A social stimulus in the form of a male pheromone markedly accelerates female sexual maturation in mice. This pheromone occurs in the high molecular weight fraction of male urine and additional research is necessary to isolate the substance in pure form. Such purification will: (a) yield the first mammalian priming pheromone, (b) permit detailed studies of its physiological and behavioral effects, and (c) provide a tool for examining the physiological basis of puberty. Puberty in female mice can also be inhibited by a component of female urine. Preliminary steps will be made to isolate this substance. An attempt will be made to test both stimulatory and inhibitory factors under semi-natural conditions.